Basis of Presentation - Line of Business Financial Performance (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Income Statement
Net interest income (taxable-equivalent basis)	$ 3,281	$ 3,227	$ 9,704	$ 9,357
Net interest income (taxable-equivalent basis), Percent change	1.70%		3.70%
Noninterest income	$ 2,408	2,331	$ 7,079	6,900
Noninterest income, Percent change	3.30%		2.60%
Securities gains (losses), net	$ 10	9	$ 25	47
Securities gains (losses), net, Percent change	11.10%		(46.80%)
Total net revenue	$ 5,699	5,567	$ 16,808	16,304
Total net revenue, Percent change	2.40%		3.10%
Noninterest expense, Percent change	1.70%		3.50%
Other intangibles, Percent change	(6.80%)		(8.40%)
Total noninterest expense, Percent change	1.50%		3.30%
Income before provision and income taxes, Percent change	3.30%		2.80%
Provision for credit losses, Percent change	(4.70%)		(4.20%)
Income before income taxes, Percent change	4.70%		4.00%
Income taxes and taxable-equivalent adjustment, Percent change	(23.40%)		(24.60%)
Net income, Percent change	16.10%		15.20%
Net (income) loss attributable to noncontrolling interests, Percent change	(16.70%)		29.00%
Net income attributable to U.S. Bancorp, Percent change	16.10%		15.50%
Noninterest expense	$ 3,003	2,954	$ 9,064	8,760
Other intangibles	41	44	120	131
Total noninterest expense	3,044	2,998	9,184	8,891
Income before provision and income taxes	2,655	2,569	7,624	7,413
Provision for credit losses	343	360	1,011	1,055
Income before income taxes	2,312	2,209	6,613	6,358
Income taxes and taxable-equivalent adjustment	490	640	1,351	1,791
Net income	1,822	1,569	5,262	4,567
Net (income) loss attributable to noncontrolling interests	(7)	(6)	(22)	(31)
Net income attributable to U.S. Bancorp	1,815	1,563	5,240	4,536
Average Balance Sheet
Commercial	$ 99,048	96,633	$ 98,295	95,347
Commercial, Percent change	2.50%		3.10%
Commercial real estate	$ 39,542	41,621	$ 39,918	42,437
Commercial real estate, Percent change	(5.00%)		(5.90%)
Residential mortgages	$ 62,042	59,030	$ 61,023	58,496
Residential mortgages, Percent change	5.10%		4.30%
Credit card	$ 21,774	20,926	$ 21,428	20,801
Credit card, Percent change	4.10%		3.00%
Other retail	$ 55,903	56,069	$ 56,135	54,835
Other retail, Percent change	(0.30%)		2.40%
Total loans, excluding covered loans	$ 278,309	274,279	$ 276,799	271,916
Total loans, excluding covered loans, Percent change	1.50%		1.80%
Covered loans	$ 2,756	3,347	$ 2,900	3,538
Covered loans, Percent change	(17.70%)		(18.00%)
Total loans	$ 281,065	277,626	$ 279,699	275,454
Total loans, Percent change	1.20%		1.50%
Goodwill, Percent change	1.00%		1.00%
Other intangible assets, Percent change	8.40%		4.90%
Assets, Percent change	1.40%		2.10%
Noninterest-bearing deposits, Percent change	(5.80%)		(4.00%)
Interest checking, Percent change	1.90%		4.20%
Savings products, Percent change	(2.10%)		(1.90%)
Time deposits, Percent change	4.60%		14.90%
Total deposits, Percent change	(1.50%)		0.50%
Total U.S. Bancorp shareholders' equity, Percent change	2.70%		2.20%
Goodwill	$ 9,459	9,365	$ 9,444	9,355
Other intangible assets	3,445	3,178	3,399	3,239
Assets	456,916	450,630	455,241	446,049
Noninterest-bearing deposits	77,192	81,964	78,546	81,808
Interest checking	69,330	68,066	69,865	67,021
Savings products	145,536	148,721	147,223	150,121
Time deposits	38,063	36,400	37,525	32,660
Total deposits	330,121	335,151	333,159	331,610
Total U.S. Bancorp shareholders' equity	50,768	49,447	50,061	48,975
Corporate and Commercial Banking [Member]
Condensed Income Statement
Net interest income (taxable-equivalent basis)	$ 739	735	$ 2,186	2,170
Net interest income (taxable-equivalent basis), Percent change	0.50%		0.70%
Noninterest income	$ 201	219	$ 632	709
Noninterest income, Percent change	(8.20%)		(10.90%)
Securities gains (losses), net				(3)
Total net revenue	$ 940	954	$ 2,818	2,876
Total net revenue, Percent change	(1.50%)		(2.00%)
Noninterest expense, Percent change	(2.60%)		0.70%
Total noninterest expense, Percent change	(2.60%)		0.70%
Income before provision and income taxes, Percent change	(0.70%)		(3.90%)
Income before income taxes, Percent change	(8.40%)		(5.50%)
Income taxes and taxable-equivalent adjustment, Percent change	(37.30%)		(35.10%)
Net income, Percent change	8.20%		11.40%
Net income attributable to U.S. Bancorp, Percent change	8.20%		11.40%
Noninterest expense	$ 379	389	$ 1,175	1,167
Other intangibles	1	1	3	3
Total noninterest expense	380	390	1,178	1,170
Income before provision and income taxes	560	564	1,640	1,706
Provision for credit losses	35	(9)	37	9
Income before income taxes	525	573	1,603	1,697
Income taxes and taxable-equivalent adjustment	131	209	401	618
Net income	394	364	1,202	1,079
Net income attributable to U.S. Bancorp	394	364	1,202	1,079
Average Balance Sheet
Commercial	$ 74,828	73,825	$ 74,781	73,179
Commercial, Percent change	1.40%		2.20%
Commercial real estate	$ 18,529	20,111	$ 18,782	20,739
Commercial real estate, Percent change	(7.90%)		(9.40%)
Residential mortgages	$ 6	6	$ 6	7
Residential mortgages, Percent change			(14.30%)
Other retail	1		$ 1
Total loans, excluding covered loans	$ 93,364	93,942	$ 93,570	93,925
Total loans, excluding covered loans, Percent change	(0.60%)		(0.40%)
Total loans	$ 93,364	93,942	$ 93,570	93,925
Total loans, Percent change	(0.60%)		(0.40%)
Other intangible assets, Percent change	(23.10%)		(21.40%)
Assets, Percent change	(0.10%)		(0.10%)
Noninterest-bearing deposits, Percent change	(8.10%)		(7.80%)
Interest checking, Percent change	(0.90%)		0.50%
Savings products, Percent change	(10.60%)		(9.30%)
Time deposits, Percent change	(5.30%)		17.00%
Total deposits, Percent change	(8.00%)		(4.20%)
Total U.S. Bancorp shareholders' equity, Percent change	4.80%		6.10%
Goodwill	$ 1,647	1,647	$ 1,647	1,647
Other intangible assets	10	13	11	14
Assets	102,146	102,267	102,417	102,520
Noninterest-bearing deposits	32,539	35,401	33,438	36,256
Interest checking	9,627	9,710	9,556	9,506
Savings products	40,356	45,138	42,227	46,556
Time deposits	18,571	19,613	17,829	15,238
Total deposits	101,093	109,862	103,050	107,556
Total U.S. Bancorp shareholders' equity	10,426	9,951	10,447	9,850
Consumer and Business Banking [Member]
Condensed Income Statement
Net interest income (taxable-equivalent basis)	$ 1,557	1,475	$ 4,587	4,337
Net interest income (taxable-equivalent basis), Percent change	5.60%		5.80%
Noninterest income	$ 582	616	$ 1,741	1,792
Noninterest income, Percent change	(5.50%)		(2.80%)
Total net revenue	$ 2,139	2,091	$ 6,328	6,129
Total net revenue, Percent change	2.30%		3.20%
Noninterest expense, Percent change	4.10%		3.50%
Other intangibles, Percent change	(12.50%)		(4.50%)
Total noninterest expense, Percent change	4.00%		3.50%
Income before provision and income taxes, Percent change	(0.20%)		2.90%
Provision for credit losses, Percent change	(41.90%)		(32.20%)
Income before income taxes, Percent change	4.90%		6.80%
Income taxes and taxable-equivalent adjustment, Percent change	(27.90%)		(26.50%)
Net income, Percent change	23.70%		25.90%
Net income attributable to U.S. Bancorp, Percent change	23.70%		25.90%
Noninterest expense	$ 1,283	1,232	$ 3,863	3,731
Other intangibles	7	8	21	22
Total noninterest expense	1,290	1,240	3,884	3,753
Income before provision and income taxes	849	851	2,444	2,376
Provision for credit losses	54	93	164	242
Income before income taxes	795	758	2,280	2,134
Income taxes and taxable-equivalent adjustment	199	276	571	777
Net income	596	482	1,709	1,357
Net income attributable to U.S. Bancorp	596	482	1,709	1,357
Average Balance Sheet
Commercial	$ 9,985	10,119	$ 9,811	9,979
Commercial, Percent change	(1.30%)		(1.70%)
Commercial real estate	$ 16,232	16,668	$ 16,318	16,742
Commercial real estate, Percent change	(2.60%)		(2.50%)
Residential mortgages	$ 58,624	56,111	$ 57,756	55,704
Residential mortgages, Percent change	4.50%		3.70%
Other retail	$ 53,742	53,830	$ 53,994	52,610
Other retail, Percent change	(0.20%)		2.60%
Total loans, excluding covered loans	$ 138,583	136,728	$ 137,879	135,035
Total loans, excluding covered loans, Percent change	1.40%		2.10%
Covered loans	$ 2,756	3,347	$ 2,900	3,531
Covered loans, Percent change	(17.70%)		(17.90%)
Total loans	$ 141,339	140,075	$ 140,779	138,566
Total loans, Percent change	0.90%		1.60%
Other intangible assets, Percent change	10.10%		7.10%
Assets, Percent change	0.50%		1.50%
Noninterest-bearing deposits, Percent change	(1.40%)		0.20%
Interest checking, Percent change	6.40%		6.60%
Savings products, Percent change	1.50%		2.20%
Time deposits, Percent change	5.80%		0.20%
Total deposits, Percent change	2.90%		3.10%
Total U.S. Bancorp shareholders' equity, Percent change	6.30%		6.20%
Goodwill	$ 3,631	3,632	$ 3,632	3,632
Other intangible assets	2,974	2,702	2,926	2,733
Assets	155,586	154,748	155,239	152,879
Noninterest-bearing deposits	28,005	28,389	27,443	27,387
Interest checking	50,319	47,301	50,052	46,938
Savings products	61,600	60,673	61,621	60,317
Time deposits	13,634	12,888	12,996	12,967
Total deposits	153,558	149,251	152,112	147,609
Total U.S. Bancorp shareholders' equity	11,847	11,147	11,850	11,154
Wealth Management and Investment Services [Member]
Condensed Income Statement
Net interest income (taxable-equivalent basis)	$ 281	252	$ 840	743
Net interest income (taxable-equivalent basis), Percent change	11.50%		13.10%
Noninterest income	$ 444	411	$ 1,305	1,221
Noninterest income, Percent change	8.00%		6.90%
Total net revenue	$ 725	663	$ 2,145	1,964
Total net revenue, Percent change	9.40%		9.20%
Noninterest expense, Percent change	6.50%		8.90%
Other intangibles, Percent change	(20.00%)		(20.00%)
Total noninterest expense, Percent change	6.10%		8.60%
Income before provision and income taxes, Percent change	14.50%		10.20%
Income before income taxes, Percent change	16.10%		10.70%
Income taxes and taxable-equivalent adjustment, Percent change	(19.60%)		(23.80%)
Net income, Percent change	36.40%		30.30%
Net income attributable to U.S. Bancorp, Percent change	36.40%		30.30%
Noninterest expense	$ 429	403	$ 1,304	1,197
Other intangibles	4	5	12	15
Total noninterest expense	433	408	1,316	1,212
Income before provision and income taxes	292	255	829	752
Provision for credit losses	(3)	1	(2)	1
Income before income taxes	295	254	831	751
Income taxes and taxable-equivalent adjustment	74	92	208	273
Net income	221	162	623	478
Net income attributable to U.S. Bancorp	221	162	623	478
Average Balance Sheet
Commercial	$ 3,783	3,506	$ 3,727	3,358
Commercial, Percent change	7.90%		11.00%
Commercial real estate	$ 529	517	$ 520	514
Commercial real estate, Percent change	2.30%		1.20%
Residential mortgages	$ 3,408	2,905	$ 3,256	2,777
Residential mortgages, Percent change	17.30%		17.20%
Other retail	$ 1,763	1,780	$ 1,728	1,757
Other retail, Percent change	(1.00%)		(1.70%)
Total loans, excluding covered loans	$ 9,483	8,708	$ 9,231	8,406
Total loans, excluding covered loans, Percent change	8.90%		9.80%
Total loans	$ 9,483	8,708	$ 9,231	8,406
Total loans, Percent change	8.90%		9.80%
Goodwill, Percent change			0.10%
Other intangible assets, Percent change	(22.80%)		(20.50%)
Assets, Percent change	8.60%		6.00%
Noninterest-bearing deposits, Percent change	(10.50%)		(5.10%)
Interest checking, Percent change	(15.10%)		(3.00%)
Savings products, Percent change	1.00%		(0.20%)
Time deposits, Percent change	10.10%		(8.70%)
Total deposits, Percent change	(3.40%)		(2.10%)
Total U.S. Bancorp shareholders' equity, Percent change	2.10%		1.80%
Goodwill	$ 1,618	1,618	$ 1,619	1,617
Other intangible assets	61	79	66	83
Assets	12,663	11,657	12,313	11,620
Noninterest-bearing deposits	13,190	14,742	14,106	14,860
Interest checking	9,351	11,016	10,220	10,534
Savings products	42,703	42,288	42,531	42,629
Time deposits	3,883	3,526	3,825	4,188
Total deposits	69,127	71,572	70,682	72,211
Total U.S. Bancorp shareholders' equity	2,486	2,434	2,471	2,428
Payment Services [Member]
Condensed Income Statement
Net interest income (taxable-equivalent basis)	$ 619	614	$ 1,822	1,792
Net interest income (taxable-equivalent basis), Percent change	0.80%		1.70%
Noninterest income	$ 911	851	$ 2,662	2,499
Noninterest income, Percent change	7.10%		6.50%
Total net revenue	$ 1,530	1,465	$ 4,484	4,291
Total net revenue, Percent change	4.40%		4.50%
Noninterest expense, Percent change	5.50%		6.80%
Other intangibles, Percent change	(3.30%)		(7.70%)
Total noninterest expense, Percent change	5.10%		6.10%
Income before provision and income taxes, Percent change	3.80%		3.00%
Provision for credit losses, Percent change	(2.20%)		2.90%
Income before income taxes, Percent change	7.20%		3.00%
Income taxes and taxable-equivalent adjustment, Percent change	(26.40%)		(29.20%)
Net income, Percent change	26.40%		21.40%
Net income attributable to U.S. Bancorp, Percent change	26.40%		23.20%
Noninterest expense	$ 713	676	$ 2,117	1,983
Other intangibles	29	30	84	91
Total noninterest expense	742	706	2,201	2,074
Income before provision and income taxes	788	759	2,283	2,217
Provision for credit losses	264	270	817	794
Income before income taxes	524	489	1,466	1,423
Income taxes and taxable-equivalent adjustment	131	178	367	518
Net income	393	311	1,099	905
Net income attributable to U.S. Bancorp	393	311	1,099	892
Average Balance Sheet
Commercial	$ 9,272	8,233	$ 8,866	7,942
Commercial, Percent change	12.60%		11.60%
Credit card	$ 21,774	20,926	$ 21,428	20,801
Credit card, Percent change	4.10%		3.00%
Other retail	$ 397	453	$ 410	466
Other retail, Percent change	(12.40%)		(12.00%)
Total loans, excluding covered loans	$ 31,443	29,612	$ 30,704	29,209
Total loans, excluding covered loans, Percent change	6.20%		5.10%
Total loans	$ 31,443	29,612	$ 30,704	29,209
Total loans, Percent change	6.20%		5.10%
Goodwill, Percent change	3.80%		3.50%
Other intangible assets, Percent change	4.20%		(3.20%)
Assets, Percent change	6.00%		5.30%
Noninterest-bearing deposits, Percent change	3.40%		6.70%
Savings products, Percent change	4.90%		5.00%
Total deposits, Percent change	3.70%		6.80%
Total U.S. Bancorp shareholders' equity, Percent change	6.10%		5.00%
Goodwill	$ 2,563	2,468	$ 2,546	2,459
Other intangible assets	400	384	396	409
Assets	37,128	35,019	36,614	34,781
Noninterest-bearing deposits	1,064	1,029	1,092	1,023
Savings products	108	103	106	101
Time deposits	3	1	3	1
Total deposits	1,175	1,133	1,201	1,125
Total U.S. Bancorp shareholders' equity	6,584	6,205	6,602	6,285
Treasury and Corporate Support [Member]
Condensed Income Statement
Net interest income (taxable-equivalent basis)	$ 85	151	$ 269	315
Net interest income (taxable-equivalent basis), Percent change	(43.70%)		(14.60%)
Noninterest income	$ 270	234	$ 739	679
Noninterest income, Percent change	15.40%		8.80%
Securities gains (losses), net	$ 10	9	$ 25	50
Securities gains (losses), net, Percent change	11.10%		(50.00%)
Total net revenue	$ 365	394	$ 1,033	1,044
Total net revenue, Percent change	(7.40%)		(1.10%)
Noninterest expense, Percent change	(21.70%)		(11.30%)
Total noninterest expense, Percent change	(21.70%)		(11.30%)
Income before provision and income taxes, Percent change	18.60%		18.20%
Income before income taxes, Percent change	28.10%		22.70%
Income taxes and taxable-equivalent adjustment, Percent change	60.90%		50.40%
Net income, Percent change	(12.80%)		(15.90%)
Net (income) loss attributable to noncontrolling interests, Percent change	(16.70%)		(22.20%)
Net income attributable to U.S. Bancorp, Percent change	(13.50%)		(16.80%)
Noninterest expense	$ 199	254	$ 605	682
Total noninterest expense	199	254	605	682
Income before provision and income taxes	166	140	428	362
Provision for credit losses	(7)	5	(5)	9
Income before income taxes	173	135	433	353
Income taxes and taxable-equivalent adjustment	(45)	(115)	(196)	(395)
Net income	218	250	629	748
Net (income) loss attributable to noncontrolling interests	(7)	(6)	(22)	(18)
Net income attributable to U.S. Bancorp	211	244	607	730
Average Balance Sheet
Commercial	$ 1,180	950	$ 1,110	889
Commercial, Percent change	24.20%		24.90%
Commercial real estate	$ 4,252	4,325	$ 4,298	4,442
Commercial real estate, Percent change	(1.70%)		(3.20%)
Residential mortgages	$ 4	8	$ 5	8
Residential mortgages, Percent change	(50.00%)		(37.50%)
Other retail		6	$ 2	2
Total loans, excluding covered loans	$ 5,436	5,289	$ 5,415	5,341
Total loans, excluding covered loans, Percent change	2.80%		1.40%
Covered loans				7
Total loans	$ 5,436	5,289	$ 5,415	5,348
Total loans, Percent change	2.80%		1.30%
Assets, Percent change	1.70%		3.10%
Noninterest-bearing deposits, Percent change	(0.40%)		8.10%
Interest checking, Percent change	(15.40%)		(14.00%)
Savings products, Percent change	48.20%		42.50%
Total deposits, Percent change	55.10%		96.70%
Total U.S. Bancorp shareholders' equity, Percent change	(1.40%)		(2.90%)
Assets	$ 149,393	146,939	$ 148,658	144,249
Noninterest-bearing deposits	2,394	2,403	2,467	2,282
Interest checking	33	39	37	43
Savings products	769	519	738	518
Time deposits	1,972	372	2,872	266
Total deposits	5,168	3,333	6,114	3,109
Total U.S. Bancorp shareholders' equity	$ 19,425	$ 19,710	$ 18,691	$ 19,258